This background information also serves as Applicant's Information Disclosure Statement.
Modern methods of housekeeping have generated a need for "sets of containers" used for such purposes as the storage of food in refrigerators or freezers and heating food in microwave ovens. The modern housewife wants a collection of containers having a range of sizes, typically from a fraction of a pint up to a gallon. The desire for a range of sizes is generated by the need to store in the refrigerator various quantities of food. Refrigerator space is precious since there always seems to be enough leftovers, etc. to fill the refrigerator to near capacity. A similar need applies to microwave ovens. It is most desireable to have a collection of containers whose sizes vary from a "one helping" size (half pint) to a gallon or half-gallon size. It is a further requirement when storing containers of food in a refrigerator that the container be equipped with a lid that is fitted very well to the container, so each container must have its own lid. Having all of these containers on hand is convenient when they are to be used. However, the problem arises as to how the container may be stored when it is not in use. Equally vexing is the problem of storing the lid so that it can be conveniently retrieved for use with its one particular container. Yet another problem is to withdraw a particular size container from a collection of containers when each container resembles a number of other containers of approximately the same size. A housewife would greatly value going to a storage shelf, and immediately withdrawing the container and its particular lid that she requires, rather than pulling out a container that "looks similar" and then sorting out the lid to fit the container from a separate pile of lids stored nearby.
Another problem associated with the containers is to maintain the temperature of the food after it has been withdrawn from the refrigerator or microwave oven. The user wants some foods (ice cream, etc.) to remain cold and other foods (soups, etc.) to remain hot.
An additional problem is that a container of cold food will tend to sweat. If the container is placed on fine furniture, water condensing on the side of the container will mar the surface of the furniture. If the container is withdrawn from a microwave oven so that is contains hot food, the container can mar a surface of fine furniture if it is laid thereon. In addition, the container may be so hot that it cannot be handled for a number of minutes.
As an example of a container of the general type to which this application is directed, U.S. Pat. No. 4,047,329 to Holt is a container intended to be used to store foods, cosmetics, medicines, nursery products, etc. The Holt container has a molded lid that snaps over an upper rim of the container in order to protect contents of the container. The lid is also designed so that the container may rest on top of the lid, in which case the container-lid arrangement is a convenient flower pot. Design of the lid is such that the flower pot can be hung with the lid attached.
U.S. Pat. No. 3,079,037 to Schecter is for a lid and container of semiflexible plastic wherein the lid can be resealed onto the top of container as required or the lid can function as a tray under the container.
There is also some prior effort directed toward conserving space required to store the containers when they are not in use.
For example, U.S. Pat. No. 1,542,115 to Weis is for a combination of containers designed so that a large container can be placed on top of two small containers.
U.S. Pat. No. 4,512,493 to Von Holdt is for a bucket having a lid designed to support a stack of buckets (one on top of another) for high stacking strength.
U.S. Pat. No. 3,338,468 to Wilson is for a receptacle that is generally rectangular receptacle wherein the lid of one container is contoured to provide for stable stacking of the containers on top each other.
Other constructions related to sealing are also disclosed in the literature such as described in U.S. Pat. No. 2,766,796 to Tupper which describes a vacuum seal.
All of these problems listed above, taken together, have not been addressed by a set of containers having a singular design.